The present invention relates to an optical sighting device and more particularly to an optical sighting device having a sighting post with an illuminated sighting mark or point and to a construction for selectively varying the magnitude of illumination of the sighting mark or point.
Optical sights are well-known and have taken a variety of forms, such as in gun sights and camera view finders. In substantially all forms, however, some type of reticle pattern is utilized to zero in on the area or object of interest. In telescopic gun sights the usual reticle is defined by black cross hairs. However, camera view finders are usually illuminated. In addition many telescopic gun sights have been made to provide an illuminated reticle. One such form is shown in U.S. Pat. No. 4,806,007 issued Feb. 21, 1989 to Glyn Bindon for Optical Gun Sight. Light or the illuminated image from this reticle pattern is located to be viewed directly through a lens system or through reflection by a mirror or lens system by which the object or field is viewed.
In using sighting devices, for example a telescopic sight for aiming weapons, it has been found that sighting with both eyes open is advantageous. When sighting with both eyes open, the operator has the benefit of binocular vision which increases the field of view, provides depth perception information, increases contrast sensitivity and assists the sense of balance. The assessment of the speed and direction of moving objects is also more accurate.
One of the objectives of the present invention is to improve the aiming speed for the viewer, such as a hunter, while using a telescopic sighting means.
With the present invention the viewer can advantageously keep both eyes open at all times while acquiring the target. In the case of a hunter the rifle is raised to an aiming position with one eye, usually the right eye, viewing the magnified target area through the eyepiece lens. As the weapon is being moved towards the target area, the magnified image becomes blurred because it is moving more rapidly than the view seen by the unmagnified (left) eye. In most cases the brain gives preference to the unmagnified view from the left eye, and this is the perceived image.
However, with a brightly illuminated aiming point of significant size, for about 96% of the population the brain merges this point with the unmagnified scene. The hunter can dynamically perceive where the weapon is pointed while moving toward the desired target. The left eye also has an extremely wide field of view, especially when compared to the narrow, magnified view seen through the telescopic sight with the right eye. This also assists the hunter to coordinate the intended target with the weapon position.
As the weapon approaches the proper position for aiming at the target, the hunter automatically slows down the movement of the weapon and the brain very quickly jumps to the complete magnified view. The hunter then makes the final precise aim for a still target, or adds an appropriate lead for a moving target. When the sighting post is in the usual vertical orientation aiming must take place at the center of the end surface at the top of the post. Prior rifle scopes have made the illuminated mark very small to allow precise aim at the tip of the post. In order for the dynamic aiming function to work with the brain as described above, the illuminated aiming mark must be of sufficient size and brightness so that it can be properly superimposed on the human perception. A small aiming mark from a small end surface on the post can impede this function. On the other hand, a large aiming mark can provide a generally imprecise mark for aiming especially where precision aiming is desired. For example it has been common to provide an aiming mark by truncating or beveling the end of an aiming post made of an optical fiber to define a single reflecting surface having a vertical D shape. With this structure the arcuate portion of the D shape is located at the top of the post and hence defines the top of the aiming mark. In order to utilize this shape as a reasonably effective sighting mark, the size of the D has been made relatively small. This, however, results in a sighting mark of limited brightness whereby it will be faint or imperceptible when viewing different scenes. On the other hand if the size of the D is enlarged to provide greater brightness, such a configuration will provide a large illuminated image which, along with the arcuate top, will result in an imprecise aiming mark which impedes accurate aiming.
In the present invention an aiming post of an optical fiber is used with an illuminated point provided at the end of the post which is of a desired, optimized, shape, size and brightness.
In order to provide an illuminated point which is well defined, the end of the fiber is beveled at selected angles to provide multiple roof surfaces which are connected to define a desirable configuration having a sharp peak or point. Depending upon the structure, one or more of the roof surfaces are then polished. The selected bevel angle, in conjunction with the suitable numerical aperture of the optical fiber, provides an aiming mark which is well defined and with a desired uniform brightness throughout the exit pupil. The terms "numerical aperture" and "exit pupil" are terms well known in the optical art and are further defined below. Thus the simple beveled end of the optical fiber provides an illuminated mark which has an advantageous shape and size. In this regard, it is believed that generally triangularly shaped roof surfaces terminating in a central point or peak provide a desired well defined mark for precise aiming.
Where the optical sight is to be used in situations varying in brightness, it is desirable to provide a generally controlled contrast between the level of brightness of the reticle and that of the target or scene being viewed. However, for day and night sighting, the aiming mark contrast can be inconsistent. For example if the aiming mark or reticle is extremely bright it may be most suitable for aiming at brightly lit target scenes but could be too bright for dimly lit target scenes and, of course, the reverse is also true.
Thus aiming at a dark object in heavy shade can be difficult or inaccurate without a suitable means to improve contrast of the aiming mark or reticle. In the past, numerous ways have been devised whereby the aiming mark brightness can be varied to improve contrast with the target scene, i.e. battery powered LEDs, electric lights, etc. which are controlled manually or electronically.
In the present invention a unique construction is utilized to vary the reticle brightness in proportion to the target scene brightness in day and night sighting including a structure for providing a selectively variable illumination intensity for day sighting whereby a desired contrast relative to that of an artificial light source for night sighting can be attained.
A unique fiber optic structure is utilized in which a fiber optic light collector receives ambient light directed radially inwardly over a selected length of fiber whereby a desired magnitude of light energy can be gathered from ambient light to provide illumination to the reticle. In addition a radio-luminescent source is used in combination with the fiber optic collector resulting in a combined illumination whereby a desired level of illumination can be provided to the reticle over the full range of brightness during day and night sighting. A unique construction for automatically varying reticle brightness in accordance with the brightness of the surrounding area by a combination of ambient light and artificial illumination is shown in U.S. Pat. No. 5,653,034 issued Aug. 5, 1997 to Glyn A. J. Bindon. One facet of the present invention provides a unique variation of that structure by utilizing a fixed level of light from an artificial light source and, in addition, providing a means for the operator to simply, selectively vary the level of ambient light illumination transmitted to the reticle.
Thus it will be seen that the unique features of the present invention provide a significant improvement over other sighting devices including ones as shown and described in the U.S. Pat. No. 2,780,130 issued Feb. 5, 1957 to Mauer, U.S. Pat. No. 3,645,635 issued Feb. 29, 1972 to Steck, U.S. Pat. No. 3,905,708 issued Sep. 16, 1975 to Steck, III, U.S. Pat. No. 3,932,162 issued Jun. 13, 1976 to Blakenship, U.S. Pat. No. 3,938,875 issued Feb. 17, 1976 to Ruder, U.S. Pat. No. 4,030,203 issued Jun. 21, 1977 to Ackerman Jr., U.S. Pat. No. 4,576,451 issued Mar. 18, 1986 to Tominaga, U.S. Pat. No. 4,665,622 issued May 19, 1987 to Idan, U.S. Pat. No. 4,764,011 issued Aug. 16, 1988 to Goldstein, U.S. Pat. No. 4,806,007 issued Feb. 21, 1989 to Bindon and U.S. Pat. No. 4,877,324 issued to Hauri et al.
Thus it is an object of the present invention to provide a unique fiber optic sighting device for telescopic sighting.
It is another object of the present invention to provide a unique fiber optic sighting device with an end surface having a unique contour for providing a well defined mark for the reticle.
It is another object of the present invention to provide a unique sighting device for telescopic sighting with both eyes opened.
It is still another object of the present invention to provide a fiber optical post for a telescopic sighting device with the post having an end surface generally triangularly shaped with a relatively sharp peak at its outer end defining the sighting reticle.
It is a general object of the present invention to provide a telescopic sighting device with an optical fiber post having a unique end surface for providing a reticle with a desired, well defined shape and desired brightness to the viewer.
It is another object of the present invention to provide a unique telescopic sighting device with improved means for illuminating the reticle.
It is still another object of the present invention to provide a unique telescopic sighting device for day and night sighting utilizing a sighting reticle illuminated by an artificial light source in combination with a light collector for collecting ambient light and in which the illumination of the reticle is varied naturally in accordance with the illumination of the target or viewing area and including means by which the level of illumination of the reticle can be further selectively adjusted by varying the amount of illumination from the light collector.
It is still another object of the present invention to provide an illuminated reticle of sufficient size and brightness and of a desired shape to allow the dynamic target acquisition described above and that functions with a zoom telescopic lens system. For example, the prism structure of the U.S. Pat. No. 4,806,007, noted above, provides the dynamic capability in a fixed magnification, but requires a cumbersome and rather expensive construction to achieve a zoom magnification feature and to provide a reticle of desired shape and brightness.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, in which: